Print medium feeding apparatus with electrode in endless belt

ABSTRACT

A print medium feeding apparatus includes an endless belt disposed to face stacked media and configured to rotate, the endless belt divided into sections having electrodes, respectively, fixed terminals configured to be in contact with two or more of the electrodes while the two or more of the electrodes are passing through a position facing the media as the electrodes are moved by rotation of the endless belt, a voltage applying unit connected to the fixed terminals and configured to apply voltage to the two or more of the electrodes that are in contact with the fixed terminals, a connection unit configured to make and break a connection between the voltage applying unit and at least one of the fixed terminals, and a switching unit configured to change a state of the connection of the connection unit in response to size of the media.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The disclosures herein relate to a print medium feeding apparatus, animage forming apparatus, and a print medium feeding system.

2. Description of the Related Art

An image forming apparatus such as a printer or a copier feeds papersheets one by one to an image forming unit by separating a paper sheetfrom a stack of paper sheets stored in a sheet tray, and uses the imageforming unit to print an image on the surface of the paper sheet, whichis then discharged to outside the apparatus. If multiple paper sheetsare fed at a time from the sheet tray, a paper jam may occur along theconveyance path or in the image forming unit, or a print failure may becaused. In order to improve the productivity of the image formingapparatus, there is a need to separate paper sheets one by one from astack of paper sheets at high speed in a stable manner.

An electrostatic adherence paper feed technology known in the art (seeJapanese Patent Application Publication No. 2010-126317, for example)uses a plurality of electrodes embedded in an insulating paper feedbelt, and applies voltage to the electrodes to polarize a paper sheetsurface that is placed in contact with the paper feed belt, therebycausing the paper sheet to adhere to the paper feed belt through anelectrostatic force to feed the paper sheet.

The electrostatic adherence paper feed technology may need to apply alarge voltage to the electrodes to create sufficient paper sheetadherence when the paper sheet to be fed is larger than the paper feedbelt. When the paper feed belt is the same size as the size of thelargest sheet among paper sheets to be fed, voltage applied to theentirety of the paper feed belt at the time of feeding a small-sizedpaper sheet may result in needless consumption of electric power.

Accordingly, it may be desirable to provide a print medium feedingapparatus that can feed a medium by the use of an appropriate amount ofelectric power responsive to the size of the medium.

SUMMARY OF THE INVENTION

It is a general object of at least one embodiment of the presentinvention to provide a print medium feeding apparatus that substantiallyobviates one or more problems caused by the limitations anddisadvantages of the related art.

In one embodiment, a print medium feeding apparatus includes an endlessbelt disposed to face stacked media and configured to rotate, theendless belt divided into sections having electrodes, respectively,fixed terminals configured to be in contact with two or more of theelectrodes while the two or more of the electrodes are passing through aposition facing the media as the electrodes are moved by rotation of theendless belt, a voltage applying unit connected to the fixed terminalsand configured to apply voltage to the two or more of the electrodesthat are in contact with the fixed terminals, a connection unitconfigured to make and break a connection between the voltage applyingunit and at least one of the fixed terminals, and a switching unitconfigured to change a state of the connection of the connection unit inresponse to size of the media.

According to at least one embodiment, a print medium feeding apparatusis provided that can feed a medium by use of an appropriate amount ofelectric power responsive to the size of the medium.

BRIEF DESCRIPTION OF THE DRAWINGS

Other objects and further features of embodiments will be apparent fromthe following detailed description when read in conjunction with theaccompanying drawings, in which:

FIG. 1 is a drawing illustrating an example of the appearance of animage forming apparatus that is provided with a paper feed apparatusaccording to a first embodiment;

FIG. 2 is a drawing illustrating an example of the schematicconfiguration of a paper feed apparatus and a paper feed cassetteaccording to the first embodiment;

FIG. 3 is a drawing illustrating an example of the hardwareconfiguration of the paper feed apparatus according to the firstembodiment;

FIG. 4 is a drawing illustrating an example of the configuration of thepaper feed apparatus according to the first embodiment;

FIGS. 5A and 5B are drawings illustrating an example of theconfiguration of a paper feed belt of the paper feed apparatus accordingto the first embodiment;

FIG. 6 is a drawing illustrating an example of another configuration ofthe paper feed apparatus according to the first embodiment;

FIG. 7 is a drawing illustrating an example of the configuration of thepaper feed apparatus according to a second embodiment;

FIG. 8 is a drawing illustrating an example of sections to which voltageis applied in response to the size and basis weight of a paper sheet inthe paper feed apparatus according to the second embodiment;

FIG. 9 is a drawing illustrating an example of the configuration of apaper feed belt of the paper feed apparatus according to a thirdembodiment;

FIG. 10 is a drawing illustrating an example of the appearance of animage forming system according to a fourth embodiment; and

FIG. 11 is a drawing illustrating an example of the hardwareconfiguration of the image forming system according to the fourthembodiment.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

In the following, embodiments will be described by referring to theaccompanying drawings. In these drawings, the same elements are referredto by the same references, and repetitive description thereof may beomitted.

First Embodiment Configuration of Image Forming Apparatus

FIG. 1 is a drawing illustrating an example of the appearance of animage forming apparatus 200 that is provided with a paper feed apparatusaccording to a first embodiment.

As illustrated in FIG. 1, the image forming apparatus 200 includes animage forming apparatus main section 201, an automatic document feeder(ADF) 202, a finisher 203 having a stapler and a shift tray, aduplex-printing buffer/flipper unit 204, an extended paper feed tray205, a one-bin discharge tray 207, an insert feeder 208, and so on.

The image forming apparatus main section 201 includes a scanner unit, animage forming unit, a developer unit, a fuser unit, and a paper feedapparatus, etc., accommodated therein, and prints an image on thesurface of a paper sheet fed from the paper feed apparatus.

The image forming apparatus main section 201 may use anelectrophotographic process to print an image on the surface of a papersheet. The process of forming an image may be a different process suchas an inkjet process. Further, it does not matter whether the process isa monochrome process or a full color process.

Configuration of Paper Feed Apparatus

FIG. 2 is a drawing illustrating an example of the schematicconfiguration of a paper feed apparatus 100 and a paper feed cassette 9according to the first embodiment.

As illustrated in FIG. 2, the paper feed apparatus 100 includes a paperfeed belt 1, a drive roller 141, a driven roller 142, and a high-voltagepower supply 121.

The paper feed belt 1 is an endless belt having a plurality ofelectrodes embedded therein that are covered with an insulating layer.The paper feed belt 1 is looped around the drive roller 141 and thedriven roller 142.

The drive roller 141 is rotated by a drive unit (not shown) to rotatethe paper feed belt 1. The driven roller 142 is rotated by the paperfeed belt 1 that is rotated by the drive roller 141.

The high-voltage power supply 121 applies voltage to the electrodes inthe paper feed belt 1 to polarize the surface of a paper sheet P comingin contact with the paper feed belt 1, thereby causing the paper sheet Pto adhere to the paper feed belt 1.

The paper feed cassette 9 storing paper sheets P includes a sheet-widthregulating guide 4, a sheet-rear-end regulating plate 5, a bottom plate6, a fan 7, an optical sensor 8, a conveyor sensor 10, and a conveyorroller 11.

The sheet-width regulating guide 4 and the sheet-rear-end regulatingplate 5 secure the paper sheets P in their place and also detect thesize of the paper sheets P upon the paper sheets P being set.

The bottom plate 6 elevates to such a height that the top of the storedpaper sheets P can be detected by the optical sensor 8, thereby raisingthe paper sheets P to the position at which paper feeding can beperformed by the paper feed apparatus 100.

The fan 7 blows air into a space over the stacked paper sheets P to flipa sheet, thereby causing the topmost paper sheet P to come in contactwith the paper feed belt 1. The paper sheet P may come in contact withthe paper feed belt 1 while voltage is applied to the embeddedelectrodes. When this happens, the surface of the paper sheet Ppolarizes, and thus adheres to the paper feed belt 1. Rotation of thepaper feed belt 1 then causes the paper sheet P to be conveyed tooutside the paper feed cassette 9.

The conveyor sensor 10 detects the paper sheet P that is fed by thepaper feed belt 1 to a conveyor path. Upon the conveyor sensor 10detecting the paper sheet P, the paper feed apparatus 100 deactivatesthe high-voltage power supply 121 to stop the adherence and conveyanceof the paper sheet P.

The conveyor roller 11 conveys the paper sheet P to the image formingunit or the like situated at the next stage as the paper sheet P is fedfrom the paper feed cassette 9 by the paper feed belt 1 of the paperfeed apparatus 100.

FIG. 3 is a drawing illustrating an example of the hardwareconfiguration of the paper feed apparatus 100 according to the firstembodiment.

As illustrated in FIG. 3, the paper feed apparatus 100 includes, inaddition to the paper feed belt 1, the high-voltage power supply 121,and so on, a CPU (Central Processing Unit) 171, an HDD (Hard Disk Drive)172, a ROM (Read Only Memory) 173, a RAM (Random Access Memory) 174, anetwork interface unit 175, a recording medium interface unit 176, etc.,which are connected to each other through a bus B.

The CPU 171 is a computing unit that performs control operations,arithmetic operations, and data processing by executing programs storedin the ROM 173 and the RAM 174. The CPU 171 performs overall control ofthe apparatus by executing programs, and also serves as a switchoverunit to select the electrodes of the paper feed belt 1 to which thehigh-voltage power supply 121 applies voltage.

The HDD 172 is a nonvolatile storage device to store various programsand data. The stored programs and data include an OS (Operating System)and application programs providing various functions.

The ROM 173 is a nonvolatile semiconductor memory (storage device) thatcan retain stored data even when the power is switched off. The RAM 174is a volatile semiconductor memory (storage device) that temporarilystores programs and data.

The network interface unit 175 is an interface with peripheral deviceshaving a communication function that are connected through a networksuch as a LAN (Local Area Network) or WAN (Wide Area Network), which isimplemented by use of wired and/or wireless data transmission lines.

The recording medium interface unit 176 is an interface with acomputer-readable recording medium 177 such as a CD-ROM, a flexible disk(FD), a CD-R, a DVD (Digital Versatile Disk), or the like, which isconnected through a data transmission line such as a USB (UniversalSerial Bus).

A predetermined program is stored in the recording medium 177. Theprogram stored in the recording medium 177 is installed in the paperfeed apparatus 100 via the recording medium interface unit 176. Theinstalled program is ready to be executed by the CPU 171.

The CPU 171, the HDD 172, the ROM 173, the RAM 174 and the like may beshared with one or more other units such as the image forming apparatusmain section 201.

FIG. 4 is a drawing illustrating an example of the configuration of thepaper feed apparatus 100 according to the first embodiment.

As illustrated in FIG. 4, the paper feed apparatus 100 includes, inaddition to the paper feed belt 1, the drive roller 141 and the drivenroller 142, the high-voltage power supply 121, a control unit 122, etc.The paper feed apparatus 100 feeds a paper sheet taken from the paperfeed cassette 9.

The paper feed belt 1 is looped around the drive roller 141 and thedriven roller 142. The paper feed belt 1 is rotated in a clockwisedirection by the drive roller 141 that rotates in the directionindicated by an arrow. The distance between the drive roller 141 and thedriven roller 142 is equivalent to the longitudinal length of an A3paper sheet. The distance between the drive roller 141 and the drivenroller 142 may be adaptively set in response to the size of the papersheet P that is to be fed.

Further, the paper feed belt 1 has four sections A through D arranged inthe rotational direction thereof. The four sections A through D havefour electrodes 101 through 104, respectively, embedded therein.

FIGS. 5A and 5B are drawings illustrating an example of theconfiguration of the paper feed belt 1 of the paper feed apparatus 100according to the first embodiment. FIG. 5A is a plan view of the sectionA and part of the section B of the paper feed belt 1 viewed from theinner side of the paper feed belt 1. FIG. 5B is a schematic view of thecross-section taken along the line a-a′ illustrated in FIG. 5A.

As illustrated in FIG. 5A, sections A and B of the paper feed belt 1have a pair of comb-shaped electrodes 101 a and 101 b and a pair ofcomb-shaped electrodes 102 a and 102 b, respectively, which are arrangedsuch that the teeth of one electrode extend in the directionperpendicular to the rotational direction of the paper feed belt 1 intothe spaces between the teeth of the other electrode. The same alsoapplies in the case of the remaining sections C and D.

It may be noted that the electrode 101 refers to the pair of electrodes101 a and 101 b, and the same applies with respect to each of theremaining electrodes 102 through 104. As illustrated in FIG. 5A and FIG.5B, the electrode 101 is covered with an insulating layer 190, exceptfor areas corresponding to openings 111 a and 111 b of the insulatinglayer 190 that are situated near the side ends of the paper feed belt 1.The same also applies in the case of the remaining electrodes 102through 104. The side ends of electrode 101 near the side ends of thepaper feed belt 1 are exposed through the openings 111 a and 111 b,respectively, toward the inner side of the paper feed belt 1. The samealso applies in the case of the remaining electrodes 102 through 104.The side ends of each of the electrodes 101 through 104 exposed throughthe openings receive a voltage applied thereto. In the section in whichvoltage is applied to the electrode, the surface of the paper feed belt1 is made to exert an adhering force to attract a paper sheet P. Becausethe electrodes 101 through 104 are covered with the insulating layer, noelectric charge moves between the electrodes. Voltage control may beperformed such that different voltages are applied to the electrodes 101through 104.

On the inner side of the paper feed belt 1, as illustrated in FIG. 4,roller-shaped, rotatable fixed terminals 131 through 134 are disposedthat are in contact with the side ends of the electrodes 101 through 104exposed through the openings. The fixed terminal 131 disposed at theposition facing the paper feed cassette 9 (not shown) is directlyconnected to the high-voltage power supply 121. The fixed terminal 132is connected through a relay 151 to the high-voltage power supply 121.The fixed terminals 133 and 134 are connected to ground. Alternativearrangement may be such that the fixed terminals 133 and 134 are notconnected to ground. Since these terminals may be charged to anuncertain potential by paper dusts and friction at the time of feedingpaper sheets P, however, the provision of a ground connection may bepreferable. The fixed terminals 131 are arranged at such intervals thatone electrode arranged in one section of the paper feed belt 1 does notcome in contact with two fixed terminals simultaneously.

The relay 151 is a connecting unit situated between the high-voltagepower supply 121 and the fixed terminal 132. The relay 151 is controlledby the control unit 122 that serves as a switchover unit for changingthe state of connection of the relay 151, thereby connecting the fixedterminal 132 either to the high-voltage power supply 121 or to ground.

The high-voltage power supply 121 applies voltage to those electrodesamong the electrodes 101 through 104 that are in contact with either thefixed terminal 131 or the fixed terminal 132 at the time of feeding apaper sheet P, thereby polarizing the surface of the paper sheet Pcoming in contact with the area of the paper feed belt 1 to which thevoltage is applied, and thus causing the paper sheet P to adhere to thepaper feed belt 1. One of the two comb-shaped electrodes included ineach of the electrodes 101 through 104 may receive a positive polarityvoltage, and the other may receive a negative polarity voltage.Alternatively, one of the two comb-shaped electrodes may be connected toground.

The control unit 122 serves as a switchover unit for changing the stateof connection of the relay 151 based on information indicative of thesize of the paper sheet P, thereby connecting the fixed terminal 132either to the high-voltage power supply 121 or to ground. The controlunit 122 obtains the information indicative of the size of the papersheet P from information entered by a user or from the results ofdetections made by the sheet-width regulating guide 4 and thesheet-rear-end regulating plate 5 of the paper feed cassette 9.

Operation of Paper Feed Apparatus During Feed Operation

A description will be given of operations performed by the paper feedapparatus 100 of the first embodiment when feeding a paper sheet P fromthe paper feed cassette 9. The paper sheets P are stored in the paperfeed cassette 9, such that they are placed against the inner wallthereof positioned on the same side as the section D.

At the time of feeding a paper sheet P, the control unit 122 obtainsinformation indicative of the size of the paper sheet P from informationentered by a user or from the results of detections made by thesheet-width regulating guide 4 and the sheet-rear-end regulating plate 5of the paper feed cassette 9.

The paper sheet P stored in the paper feed cassette 9 may be A3portrait. In this case, the control unit 122 controls the state ofconnection of the relay 151 to connect the fixed terminal 132 to thehigh-voltage power supply 121. In this state, the high-voltage powersupply 121 supplies voltage. When the paper feed belt 1 is in such aposition as illustrated in FIG. 4, the voltage is applied to theelectrode 104 of the section D being in contact with the fixed terminal131 and to the electrode 103 of the section C being in contact with thefixed terminal 132. As the paper feed belt 1 rotates, differentelectrodes successively come in contact with the fixed terminals 131 and132. Despite this, the two sections of the paper feed belt 1 that facethe paper feed cassette 9 always have the electrodes thereof receivingthe voltage, thereby exerting an adhering force to attract the papersheet P.

The paper sheet P stored in the paper feed cassette 9 may be A4landscape. In this case, the control unit 132 controls the state ofconnection of the relay 151 to connect the fixed terminal 132 to ground.In this state, the high-voltage power supply 121 supplies voltage. Whenthe paper feed belt 1 is in such a position as illustrated in FIG. 4,voltage is applied only to the electrode 104 of the section D being incontact with the fixed terminal 131. As the paper feed belt 1 rotates,different electrodes successively come in contact with the fixedterminal 131. Despite this, the section of the paper feed belt 1 thatfaces the paper feed cassette 9 always has the electrode thereofreceiving the voltage, thereby exerting an adhering force to attract thepaper sheet P.

In this manner, control is performed based on the information indicativeof the size of a paper sheet P, such that the fixed terminal 132 isconnected to the high-voltage power supply 121 when feeding a large-sizepaper sheet P, and is not connected to the high-voltage power supply 121when feeding a small-size paper sheet P. Through such control, thelarge-size paper sheet can be reliably fed, and, also, needlessconsumption of electric power is avoided by applying voltage to theelectrode(s) of the fewest necessary section(s) when feeding thesmall-size paper sheet P.

Further, as illustrated in FIG. 6, a remaining charge removing powersupply 123 may be provided and connected to the fixed terminals 133 and134. The remaining charge removing power supply 123 applies the voltagefor removing remaining charge to an electrode that comes in contact withthe fixed terminals 133 and 134 after this electrode receives thevoltage of the high-voltage power supply 121 while being in contact withthe fixed terminal 131 and disconnects from the fixed terminal 131 asthe paper feed belt 1 rotates. An effective method to remove remainingcharge is to apply an alternating voltage to the electrode while makingthe amplitude of the alternating voltage smaller and smaller. Theremaining charge removing power supply 123 may thus be preferably analternating current power supply and a pulse-voltage power supplycapable of applying voltages of opposite polarities, and may preferablyapply the voltage to the electrode until the amplitude of the voltagereaches 0 V.

The fixed terminals 132, 133 and 134 are connected either to theremaining charge removing power supply 123 or to ground through relays151 through 154 whose connection states are controlled by the controlunit 122.

In the paper feed apparatus 100, charge may remain in an electrode towhich the high-voltage power supply 121 applies high voltage in order tofeed a heavy basis weight paper sheet P, for example. In such a case,the control unit 122 connects the remaining charge removing power supply123 to the fixed terminal to which the high-voltage power supply 121does not supply voltage, so that an alternating voltage as describedabove is applied to each electrode to remove remaining charge.

Voltage applied by the high-voltage power supply 121 to an electrode maybe small when feeding a light basis weight paper sheet P. In this case,remaining charge may not be in existence. The control unit 122 thuscontrols the connection state of the relays 151 through 154 such thatthe fixed terminals not connected to the high-voltage power supply 121are connected to ground.

As described above, the remaining charge removing power supply 123 isprovided to remove charge remaining in each electrode. This arrangementprevents the paper feed belt 1 from exerting a needless adhering force,thereby ensuring a reliable feeding operation of the paper feedapparatus 100.

As described heretofore, the paper feed apparatus 100 of the firstembodiment uses the control unit 122, which changes the state ofconnection of the relay 151 in response to information indicative of thesize of a paper sheet P to change the sections to which the high-voltagepower supply 121 applies voltage, thereby attracting and feeding thepaper sheet P by use of proper electric power responsive to the size ofthe paper sheet P. Compared to the case in which the paper sheet P isconveyed by applying voltage to all the electrodes embedded in the paperfeed belt 1, for example, power consumption is reduced to a half whenconveying an A3 portrait paper sheet P, and power consumption is reducedto a quarter when conveying an A4 landscape paper sheet P. Further, thehigh-voltage power supply 121 may be powered off while feeding is notperformed during an interval between paper sheets, which achievesfurther reduction in power consumption. Moreover, the provision of theremaining charge removing power supply 123 makes it possible to feed apaper sheet P in a more reliable manner.

The description of the first embodiment has been given with respect toan example in which the paper feed belt 1 is divided into the foursections A through D in a rotational direction. This is not a limitingexample, and the number of divided sections may be two or more. Thenumber of sections may be increased to properly cope with an increasedvariety of paper sheet sizes, and voltage is applied in response to thesize of a paper sheet P to feed the paper sheet P by use of properelectric power while reducing needless power consumption.

Second Embodiment

In the following, a second embodiment will be described with referenceto the accompanying drawings. A description will be omitted of the sameelements as those of the embodiment already described.

<Configuration of Paper Feed Apparatus>

The paper feed apparatus 100 of the second embodiment differs from thatof the first embodiment in that the paper feed belt 1 is divided intosections in a direction perpendicular to the rotational direction.

FIG. 7 is a drawing illustrating an example of the configuration of thepaper feed apparatus 100 according to the second embodiment.

As illustrated in FIG. 7, the paper feed belt 1 is divided into sectionsA through C in a direction perpendicular to the rotational direction.The sections A through C have a pair of comb-shaped electrodes 101 a and101 b, a pair of comb-shaped electrodes 105 a and 105 b, and a pair ofcomb-shaped electrodes 106 a and 106 b, respectively, which are arrangedsuch that the teeth of one electrode of a given pair extend in thedirection perpendicular to the rotational direction of the paper feedbelt 1 into the spaces between the teeth of the other electrode of thegiven pair. Electrodes 101 a and 101 b are collectively referred to asan electrode 101. This also applies to other electrodes.

The paper feed belt 1 has a width (i.e., the span in the directionperpendicular to the rotational direction) equal to the longitudinallength of an A3 size paper sheet. The divided sections A through C areprovided such that their widths satisfy the following relationships: aratio of the width of the section A to the width of the sectionB=1:(2^(0.5)−1), and a ratio of the combined width of the sections A andB to the width of the section C=1:(2^(0.5)−1). The widths and numbers ofdivided sections may be set differently as appropriate.

The electrodes 101, 105 and 106 provided in the respective sections Athrough C are covered with the insulating layer 190. The side ends ofthe electrodes 101, 105 and 106 opposite to each other in the directionperpendicular to the rotational direction are exposed through openings111 a and 111 b, 112 a and 112 b, and 113 a and 113 b, respectively.

Fixed terminals that come in contact with the side ends of theelectrodes 101, 105 and 106 through the openings in the sections Athrough C are provided on the inner side of the paper feed belt 1. Thesefixed terminals are connected either to high-voltage power supply 121 aor 121 b or to ground through relays 155 a, 155 b, 156 a and 156 b whoseconnection states are controlled by the control unit 122.

The high-voltage power supply 121 a is connected to the electrodes 101a, 105 a and 106 a through fixed terminals. The high-voltage powersupply 121 b is connected to the electrodes 101 b, 105 b and 106 bthrough fixed terminals. The high-voltage power supplies 121 a and 121 bproduce voltages of opposite polarities, respectively.

The control unit 122 changes the state of connection of the relays 155a, 155 b, 156 a and 156 b situated between the fixed terminals and thehigh-voltage power supplies 121 a and 121 b based on informationindicative of the size of a paper sheet P fed by the paper feedapparatus 100.

<Operation of Paper Feed Apparatus During Feed Operation>

The paper sheets P are stored in the paper feed cassette 9 facing thepaper feed belt 1, such that they are placed against the top rightcorner of the paper feed cassette 9 (wherein the term “top right” isdefined with respect to the positional arrangements illustrated in FIG.7). A description will be given of an operation of feeding a paper sheetP in the paper feed apparatus 100.

At the time of feeding a paper sheet P, the control unit 122 obtainsinformation indicative of the size of the paper sheet P from informationentered by a user or from the results of detections made by thesheet-width regulating guide 4 and the sheet-rear-end regulating plate 5of the paper feed cassette 9.

The paper sheet P stored in the paper feed cassette 9 may be A5portrait. In this case, the control unit 122 controls the relays 155 a,155 b, 156 a and 156 b to connect the electrode 105 of the section B andthe electrode 106 of the section C to ground. The high-voltage powersupply 121 applies voltage only to the electrode 101 of the section A ofthe paper feed belt 1, so that the paper feed belt 1 attracts andconveys the A5 portrait sheet P by use of only the section A.

When an A4 portrait paper sheet P is to be conveyed, the control unit122 controls the relays 156 a and 156 b to connect the electrode 105 ofthe section B to the high-voltage power supply 121, and controls therelays 155 a and 155 b to connect the electrode 106 of the section C toground. The high-voltage power supply 121 applies voltage to theelectrode 101 of the section A and to the electrode 105 of the sectionB, so that the paper feed belt 1 attracts and conveys the A4 portraitsheet P by use of the section A and the section B.

When an A3 portrait paper sheet P is to be conveyed, the control unit122 controls the state of connection of the relays to connect theelectrode 105 of the section B and the electrode 106 of the section C tothe high-voltage power supply 121. In this case, the paper feed belt 1attracts and conveys the A3 portrait sheet P by use of all the sectionsA, B and C.

Moreover, the control unit 122 may change the sections to which to applyvoltage in response to the size and basis weight of a paper sheet P tobe fed, based on information indicative of a sheet type entered by auser.

FIG. 8 is a drawing illustrating an example of sections to which voltageis applied in response to the size and basis weight of a paper sheet inthe paper feed apparatus 100 according to the second embodiment.

As illustrated in FIG. 8, in the case of the A5-size paper sheet P, thecontrol unit 122 controls the states of connection of the relays 155 a,155 b, 156 a and 156 b in such a manner as to apply voltage to theelectrode of the section A regardless of the basis weight. In the caseof the A4-size paper sheet P, the control unit 122 controls the statesof connection of the relays 155 a, 155 b, 156 a and 156 b in such amanner as to apply voltage to the electrodes in all the sections Athrough C regardless of the basis weight.

In the case of a B5-size paper sheet P being conveyed, the control unit122 controls the states of connection of the relays 155 a, 155 b, 156 aand 156 b in such a manner as to apply voltage to the electrodes of thesections A and B for a heavy basis weight sheet and to apply voltage tothe electrode of only the section A for a light basis weight sheet. Inthe case of the B4-size paper sheet P being conveyed, the control unit122 controls the states of connection of the relays 155 a, 155 b, 156 aand 156 b in such a manner as to apply voltage to the electrodes in allthe sections A through C for a heavy basis weight sheet and to applyvoltage to the electrodes of only the sections A and B for a light basisweight sheet.

In this manner, the sections to which voltage is applied are changed inresponse to the size and basis weight of paper sheets P, so that thepaper sheets P are properly conveyed and fed with proper powerconsumption even when the paper sheets P having the same size havedifferent weights due to difference in paper type.

As described heretofore, the paper feed apparatus 100 of the secondembodiment uses the control unit 122, which changes the states ofconnection of the relays 155 a, 155 b, 156 a and 156 b in response tothe size and basis weight of a paper sheet P to be fed wherein the sizeis measured in the direction perpendicular to the rotational directionof the paper feed belt 1, thereby to change the sections to which thehigh-voltage power supply 121 applies voltage. Accordingly, the papersheet P is attracted and fed by using a proper amount of electric powerfor the size and basis weight of the paper sheet P. Compared to the casein which the paper sheet P is conveyed by applying voltage to all theelectrodes embedded in the paper feed belt 1, for example, powerconsumption is reduced to three tenths when feeding an A5 portrait papersheet P, and power consumption is reduced to a half when feeding an A3portrait paper sheet P. Further, the high-voltage power supply 121 maybe powered off while feeding is not performed during an interval betweenpaper sheets, which achieves further reduction in power consumption.

The description of the second embodiment has been given with respect toan example in which the paper feed belt 1 is divided into the threesections A through C in the direction perpendicular to the rotationaldirection. This is not a limiting example, and the number of dividedsections may be two or more. The number of sections may be increased toproperly cope with an increased variety of paper sheet sizes and types,and voltage is applied in response to the size of a paper sheet P tofeed the paper sheet P by use of proper electric power.

Third Embodiment

In the following, a third embodiment will be described with reference tothe accompanying drawings. A description will be omitted of the sameelements as those of the embodiments already described.

The paper feed apparatus 100 of the third embodiment differs from thatof the first embodiment and the second embodiment in that the paper feedbelt 1 is divided into sections in the rotational direction as well asin the direction perpendicular to the rotational direction.

The paper feed belt 1 of the third embodiment is divided into four areasin the rotational direction and further divided into three sections inthe direction perpendicular to the rotational direction. In total,twelve sections A1, B1, C1, . . . , A4, B4, and C4 are created.

FIG. 9 is a drawing illustrating an example of the configuration of thepaper feed belt 1 used by the paper feed apparatus 100 of the thirdembodiment. FIG. 9 is a plan view of the paper feed belt 1 as viewedfrom the inner side of the loop to show the areas A1, B1, C1, A2, B2,and C2 of the paper feed belt 1.

As illustrated in FIG. 9, the paper feed belt 1 has in each of thedivided sections a pair of comb-shaped electrodes, which are arrangedsuch that the teeth of one electrode extend in the directionperpendicular to the rotational direction into the spaces between theteeth of the other electrode.

The electrodes provided in the respective sections are partially coveredwith the insulating layer 190, and are exposed toward the inner side ofthe paper feed belt 1 through openings that are formed at side ends ofthe electrodes opposite to each other in the direction perpendicular tothe rotational direction.

Fixed terminals are disposed on the inner side of the paper feed belt 1to come in contact with the side ends of the electrodes at the positionfacing the paper sheets P stored in the paper feed cassette 9. Each ofthe fixed terminals is connected either to the high-voltage power supplyor to ground through relays whose state of connection is changed by thecontrol unit.

The control unit changes the state of connection of the relays situatedbetween the high-voltage power supply and the fixed terminals inresponse to the size of or the size and basis weight of the paper sheetP to be fed by the paper feed apparatus 100, thereby changing theelectrodes to which the high-voltage power supply applies voltage at thetime of feeding the paper sheet P.

In this manner, electrodes are provided in the sections into which thepaper feed belt 1 is divided in the rotational direction as well as inthe direction perpendicular to the rotational direction, and theelectrodes to which voltage is applied are selected in response to thesize, basis weight, and/or the like of the paper sheet P. Thisarrangement can feed paper sheets P of various sizes and types by use ofproper electric power while reducing needless power consumption.

Fourth Embodiment

In the following, a fourth embodiment will be described with referenceto the accompanying drawings. A description will be omitted of the sameelements as those of the embodiments already described.

FIG. 10 is a drawing illustrating an example of the configuration of animage forming system 400 according to the fourth embodiment.

The image forming system 400 of the fourth embodiment is a productionprinting system in which an image forming apparatus 200 is provided withperipheral units having functions such as feeding, folding, stapling,cutting, etc., which may be combined at the time of use according toneed. The image forming system 400 of the fourth embodiment includes alarge volume paper feed unit 211, an inserter 212, a folding unit 213, afinisher 214 for stapling and punching, a cutter 215, and an informationprocessing apparatus 300, which are connected to the image formingapparatus 200.

FIG. 11 is a drawing illustrating an example of the hardwareconfiguration of the image forming system 400 according to the fourthembodiment.

The information processing apparatus 300 includes a network interfaceunit 301, a ROM 302, a RAM 303, a CPU 304, an HDD 305, and an interfaceunit 306, which are connected to each other through a bus B1. Theinformation processing apparatus 300 is connected to the image formingapparatus 200 through a dedicated line 210.

The CPU 300 of the information processing apparatus 300 is a computingunit that performs control operations, arithmetic operations, and dataprocessing by executing programs stored in the ROM 302 and the RAM 303.Further, the CPU 304 performs overall control of the apparatus byexecuting programs, and also serves as a control unit of a paper feedunit 403 of the image forming apparatus 200.

The HDD 305 is a nonvolatile storage device to store various programsand data. The stored programs and data include an OS (Operating System)and application programs providing various functions.

The ROM 302 is a nonvolatile semiconductor memory (storage device) thatcan retain stored data even when the power is switched off. The RAM 303is a volatile semiconductor memory (storage device) that temporarilystores programs and data.

The network interface unit 301 is an interface with peripheral devicessuch as PCs 501 through 503 having a communication function that areconnected through a network 500 such as a LAN or WAN, which isimplemented by use of wired and/or wireless data transmission lines.

The interface unit 306 is used to connect the information processingapparatus 300 to the image forming apparatus 200, and is connected to aninterface unit 403 of the image forming apparatus 200 through thededicated line 210.

The image forming apparatus 200 connected to the information processingapparatus 300 through the dedicated line 210 includes a printing unit401, a display unit 402, a paper feed unit 403, an interface unit 404,an operation unit 405, and a miscellaneous interface unit 406, which areconnected to each other through a bus B2.

The printing unit 401 includes a photosensitive unit, a fuser unit,etc., and forms an image on the surface of a paper sheet P based onimage data.

The display unit 402 and the operation unit 405 are formed of keyswitches (i.e., hard keys) and an LCD (liquid crystal display) that hasa touch panel function (inclusive of software keys implemented bygraphical user interface). The display unit 402 and the operation unit405 are a display and input apparatus serving as a user interface thatis used to exploit the functions of the image forming apparatus 200.Using the display unit 402 and the operation unit 405, a user may enterinformation indicative of the size or the like of the paper sheet P tobe printed.

The paper feed unit 403 is the paper feed apparatus 100 of the firstembodiment, and feeds a paper sheet P stored in a paper feed cassette tothe printing unit 401.

The interface unit 404 is used for connection to the informationprocessing apparatus 300, and is connected to the interface unit 306 ofthe information processing apparatus 300 through the dedicated line 210.

The image forming system 400 having the configuration described aboveuses the CPU 304 of the information processing apparatus 300 to controlthe state of connection of relays situated between the electrodes of thepaper feed belt 1 and the high-voltage power supply in the paper feedunit 403 of the image forming apparatus 200. This arrangement serves tofeed a paper sheet P by use of optimal conditions for applying voltage.

It is preferable to connect the image forming apparatus 200 to theinformation processing apparatus 300 through the dedicated line 210since such a connection allows the paper feed unit 403 of the imageforming apparatus 200 to be controlled at high speed. As long as thecontrol of the paper feed unit 403 is performed at high speed, theconnection may be provided by use of a network or the like.

The paper feed unit 403 of the image forming apparatus 200 may be thepaper feed apparatus 100 of the second or third embodiment. Regardlessof the configuration used, a paper sheet P can be fed under properelectric power conditions without consuming needless electric power inresponse to the size, basis weight, and/or the like of the paper sheetP.

The function of the CPU 304 of the information processing apparatus 300to serve as a control unit to control the paper feed unit 403 of theimage forming apparatus 200 may be provided in the image formingapparatus 200, or may be provided in the PC 501 or the like connectedthrough a network or the like.

Although the present invention has been described heretofore byreferring to one or more embodiments, the present invention is notlimited to such embodiments. Various variations and modifications may bemade without departing from the scope of the present invention.

The present application is based on Japanese priority application No.2012-052869 filed on Mar. 9, 2012, with the Japanese Patent Office, theentire contents of which are hereby incorporated by reference.

What is claimed is:
 1. A print medium feeding apparatus, comprising: anendless belt disposed to face stacked media and configured to rotate,the endless belt divided into sections having electrodes, respectively;fixed terminals configured to be in contact with two or more of theelectrodes while the two or more of the electrodes are passing through aposition facing the media as the electrodes are moved by rotation of theendless belt; a voltage applying unit connected to the fixed terminalsand configured to apply voltage to the two or more of the electrodesthat are in contact with the fixed terminals; a connection unitconfigured to make and break a connection between the voltage applyingunit and at least one of the fixed terminals; and a switching unitconfigured to change a state of the connection of the connection unit inresponse to size of the media.
 2. The print medium feeding apparatus asclaimed in claim 1, wherein the sections of the endless belt are formedby dividing the endless belt in a rotational direction thereof.
 3. Theprint medium feeding apparatus as claimed in claim 1, wherein thesections of the endless belt are formed by dividing the endless belt ina direction perpendicular to a rotational direction thereof.
 4. Theprint medium feeding apparatus as claimed in claim 3, wherein theswitching unit is configured to change the state of the connection ofthe connection unit in response to basis weight of the media.
 5. Theprint medium feeding apparatus as claimed in claim 1, further comprisinga remaining charge removing unit configured to apply alternating voltageto the electrodes to which the voltage applying unit has applied thevoltage.
 6. The print medium feeding apparatus as claimed in claim 1,further comprising a ground unit configured to connect, to a ground, oneor more electrodes among the electrodes of the endless belt, which oneor more electrodes are not receiving the voltage applied by the voltageapplying unit.
 7. The print medium feeding apparatus as claimed in claim1, wherein each of the electrodes is a pair of comb-shaped electrodes,which are arranged such that teeth of one of the comb-shaped electrodesextend in a direction perpendicular to a rotational direction of theendless belt into spaces between teeth of another of the comb-shapedelectrodes.
 8. An image forming apparatus, comprising the print mediumfeeding apparatus claimed in claim
 1. 9. A system, comprising: a printmedium feeding apparatus configured to feed a medium; and an informationprocessing apparatus, wherein the print medium feeding apparatusincludes: an endless belt disposed to face stacked media and configuredto rotate, the endless belt divided into sections having electrodes,respectively; fixed terminals configured to be in contact with two ormore of the electrodes while the two or more of the electrodes arepassing through a position facing the media as the electrodes are movedby rotation of the endless belt; a voltage applying unit connected tothe fixed terminals and configured to apply voltage to the two or moreof the electrodes that are in contact with the fixed terminals; and aconnection unit configured to make and break a connection between thevoltage applying unit and at least one of the fixed terminals, whereinthe information processing apparatus includes a switching unitconfigured to change a state of the connection of the connection unit inresponse to size of the media.
 10. A method of feeding a medium,comprising: rotating an endless belt disposed to face stacked media, theendless belt divided into sections having electrodes, respectively;applying voltage to one or more of the electrodes while the one or moreof the electrodes are passing through a position facing the media as theelectrodes are moved by rotation of the endless belt, wherein a numberof the electrodes to which the voltage is applied is changed in responseto size of the media.